[svn-r8791] Purpose: Rewrote metadata cache (H5AC.c, etc.) to improve performance.

Description:

Replaced the old metadata cache with a cache with a modified LRU
replacement policy.  This should improve the hit rate.

Solution:

Since we want to flush cache entries in increasing address order, I
used the threaded binary B-tree code to store the cache entries.
There is a fair bit of overhead here, so we may want to consider
other options.

While the code is designed to allow the support of other replacement
algorithms, at present, only a modified version of LRU is supported.

The modified LRU algorithm requires that a user selectable portion
of the cache entries be clean.  The clean entries are evicted first
when writes are not permitted.  If the pool of clean entries is used
up, the cache grows beyond its user specified maximum size.  The
cache can also exceed its maximum size if the combined size of the
protected (or locked) entries exceeds the maximum size of the cache.


Platforms tested:

eirene (serial, parallel, fp), h5committested


Misc. update:

1 files changed, 48 insertions, 49 deletions

diff --git a/src/H5ACprivate.h b/src/H5ACprivate.h
index f12f397..6acc3e3 100644
--- a/src/H5ACprivate.h
+++ b/src/H5ACprivate.h
@@ -21,7 +21,9 @@
  * Purpose:		Constants and typedefs available to the rest of the
  *			library.
  *
- * Modifications:
+ * Modifications:	JRM - 6/4/04
+ *			Complete re-write for a new caching algorithm
+ *			located in H5C.c
  *
  *-------------------------------------------------------------------------
  */
@@ -29,21 +31,20 @@
 #ifndef _H5ACprivate_H
 #define _H5ACprivate_H
 
-#include "H5ACpublic.h"		/*public prototypes			     */
+#include "H5ACpublic.h"		/*public prototypes			*/
 
 /* Pivate headers needed by this header */
 #include "H5private.h"		/* Generic Functions			*/
 #include "H5Fprivate.h"		/* File access				*/
+#include "H5Cprivate.h"		/* cache				*/
 
-/*
- * Feature: Define H5AC_DEBUG on the compiler command line if you want to
- *	    debug H5AC_protect() and H5AC_unprotect() by insuring that
- *	    nothing  accesses protected objects.  NDEBUG must not be defined
- *	    in order for this to have any effect.
- */
-#ifdef NDEBUG
-#  undef H5AC_DEBUG
-#endif
+
+#define H5AC_BT_ID	0	/*B-tree nodes				     */
+#define H5AC_SNODE_ID	1	/*symbol table nodes			     */
+#define H5AC_LHEAP_ID	2	/*local heap				     */
+#define H5AC_GHEAP_ID	3	/*global heap				     */
+#define H5AC_OHDR_ID	4	/*object header				     */
+#define H5AC_NTYPES	5	
 
 /*
  * Class methods pertaining to caching.	 Each type of cached object will
@@ -64,28 +65,38 @@
  * DEST:	Just frees memory allocated by the LOAD method.
  *
  * CLEAR:	Just marks object as non-dirty.
+ *
+ * SIZE:	Report the size (on disk) of the specified cache object.
+ *		Note that the space allocated on disk may not be contiguous.
+ */
+
+typedef H5C_load_func_t		H5AC_load_func_t;
+typedef H5C_flush_func_t	H5AC_flush_func_t;
+typedef H5C_dest_func_t		H5AC_dest_func_t;
+typedef H5C_clear_func_t	H5AC_clear_func_t;
+typedef H5C_size_func_t		H5AC_size_func_t;
+
+typedef H5C_class_t		H5AC_class_t;
+
+
+/* The H5AC_NSLOTS #define is now obsolete, as the metadata cache no longer
+ * uses slots.  However I am leaving it in for now to avoid modifying the
+ * interface between the metadata cache and the rest of HDF.  It should
+ * be removed when we get to dealing with the size_hint parameter in
+ * H5AC_create().
+ *						JRM - 5/20/04
+ *
+ * Old comment on H5AC_NSLOTS follows:
+ *
+ * A cache has a certain number of entries.  Objects are mapped into a
+ * cache entry by hashing the object's file address.  Each file has its
+ * own cache, an array of slots.
  */
-typedef enum H5AC_subid_t {
-    H5AC_BT_ID		= 0,	/*B-tree nodes				     */
-    H5AC_SNODE_ID	= 1,	/*symbol table nodes			     */
-    H5AC_LHEAP_ID	= 2,	/*local heap				     */
-    H5AC_GHEAP_ID	= 3,	/*global heap				     */
-    H5AC_OHDR_ID	= 4,	/*object header				     */
-    H5AC_NTYPES		= 5	/*THIS MUST BE LAST!			     */
-} H5AC_subid_t;
-
-typedef void *(*H5AC_load_func_t)(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *udata1, void *udata2);
-typedef herr_t (*H5AC_flush_func_t)(H5F_t *f, hid_t dxpl_id, hbool_t dest, haddr_t addr, void *thing);
-typedef herr_t (*H5AC_dest_func_t)(H5F_t *f, void *thing);
-typedef herr_t (*H5AC_clear_func_t)(H5F_t *f, void *thing, hbool_t dest);
-
-typedef struct H5AC_class_t {
-    H5AC_subid_t            id;
-    H5AC_load_func_t        load;
-    H5AC_flush_func_t       flush;
-    H5AC_dest_func_t        dest;
-    H5AC_clear_func_t       clear;
-} H5AC_class_t;
+#define H5AC_NSLOTS     10330           /* The library "likes" this number... */
+
+
+typedef H5C_cache_entry_t	H5AC_info_t;
+
 
 /*===----------------------------------------------------------------------===
  *                             Protect Types
@@ -95,27 +106,15 @@ typedef struct H5AC_class_t {
  * type of operation you're planning on doing to the metadata. The
  * Flexible Parallel HDF5 locking can then act accordingly.
  */
+
 typedef enum H5AC_protect_t {
     H5AC_WRITE,                 /* Protect object for writing                */
     H5AC_READ                   /* Protect object for reading                */
 } H5AC_protect_t;
 
-/*
- * A cache has a certain number of entries.  Objects are mapped into a
- * cache entry by hashing the object's file address.  Each file has its
- * own cache, an array of slots.
- */
-#define H5AC_NSLOTS	10330		/* The library "likes" this number... */
 
-typedef struct H5AC_info_t {
-    const H5AC_class_t	*type;		/*type of object stored here	     */
-    haddr_t		addr;		/*file address for object	     */
-    hbool_t             dirty;          /* 'Dirty' flag for cached object */
-} H5AC_info_t;
-typedef H5AC_info_t *H5AC_info_ptr_t;   /* Typedef for free lists */
-
-/* Typedef for metadata cache (defined in H5AC.c) */
-typedef struct H5AC_t H5AC_t;
+/* Typedef for metadata cache (defined in H5C.c) */
+typedef H5C_t	H5AC_t;
 
 /* Metadata specific properties for FAPL */
 /* (Only used for parallel I/O) */
@@ -158,9 +157,9 @@ H5_DLL herr_t H5AC_flush(H5F_t *f, hid_t dxpl_id, const H5AC_class_t *type, hadd
 H5_DLL herr_t H5AC_rename(H5F_t *f, hid_t dxpl_id, const H5AC_class_t *type,
 			   haddr_t old_addr, haddr_t new_addr);
 H5_DLL herr_t H5AC_dest(H5F_t *f, hid_t dxpl_id);
-#ifdef H5AC_DEBUG
+
 H5_DLL herr_t H5AC_stats(H5F_t *f);
-#endif /* H5AC_DEBUG */
+
 
 #endif /* !_H5ACprivate_H */